Homogeneous ionic transition metal catalysts are known for their high catalytic activity in addition polymerizations, especially those of olefins and diolefins, and are capable of providing olefinic polymers of narrow molecular weight distributions and, for example when ethylene is copolymerized with a further alpha-olefin, narrow comonomer distributions. Under polymerization conditions where polymer is formed as solid particles, for example, in gas phase or slurry phase polymerizations, these homogeneous (soluble) catalysts form polymer deposits on reactor walls and stirrers which deposits should be removed frequently as they prevent an efficient heat-exchange necessary for cooling the reactor contents, prevent the regular or continuous removal of polymer from the reactor, and cause excessive wear of the moving parts in the reactor. The polymers produced by these soluble catalysts further have undesirable particle characteristics such as a low bulk density which limits the commercial utility of both the polymer and the process. Therefore, there is a need to provide catalysts that would overcome such problems.
Several supported catalysts have been proposed for use in particle forming polymerization processes. Support materials in the prior art are typically employed in combination with catalytic components to obtain the formation of polymer particles of desirable particle size and morphology. Secondly, support materials are used to increase catalytic activity per unit of active components by depositing such components on a support material having a relatively high surface area. Furthermore, support materials are employed for anchoring thereon the catalytic components to avoid the presence of significant amounts of catalyst which under particle forming polymerization conditions becomes solubilized and gives rise to particles of undesired size and morphology said particles contributing to the formation of polymer deposits at reactor walls and other moving parts in the reactor.
EP-327649 and EP-725086 describe solid catalysts using alumoxanes as cocatalyst. EP-327649 relates to a nonsupported olefin polymerization catalyst composed of a transition metal compound and an alumoxane having an average particle size of 5 to 200 micrometers and a specific surface area of 20 to 1,000 m.sup.2 /g. EP-725086 describes a solid component of a catalyst for ethylene and alpha-olefins (co)polymerization comprising a metallocene supported on an inorganic solid carrier, where a carbon atom of one of the .eta..sup.5 -cyclopentadienyl rings coordinated to the transition metal is covalently bonded to a metal atom of the inorganic solid carrier. This solid component is typically used with an organic aluminum oxy-derivative which is usually alumoxane.
Supported nonalumoxane catalysts are disclosed, for example, in EP-418044, EP-522581, WO-91/09882, WO-94/03506, WO-9403509, and WO-9407927. These describe supported catalysts obtained by combining a transition metal compound, an activator component comprising a cation capable of reacting with a transition metal compound and a bulky, labile anion capable of stabilizing the metal cation formed as a result of reaction between the metal compound and the activator component, and a catalyst support material. In EP-522581 and WO-9407927 additionally an organometal compound, typically an organoaluminum compound is employed.
EP-727443 describes an olefin polymerization catalyst obtainable by contacting a transition metal compound, an organometallic compound, and a solid catalyst component comprising a carrier and an ionized ionic compound capable of forming a stable anion on reaction with said transition metal compound, wherein said ionized ionic compound comprises a cationic component and an anionic component and said cationic component is fixed on the surface of the carrier.
WO-96/04319 describes a catalyst composition comprising a metal oxide support having covalently bound to the surface thereof directly through the oxygen atom of the metal oxide, an activator anion that is also ionically bound to a catalytically active transition metal compound.
WO-93/11172 relates to polyanionic moieties comprising a plurality of noncoordinating anionic groups pendant from and chemically bonded to a core component. The core component may be a cross-linked polystyrene or polydivinylbenzene polymeric core or a polyanionic Lewis basic core substrate reactable with a Lewis acid. The polyanionic moieties are used in a noncoordinating association with cationic transition metal compounds.
Copending U.S. application Ser. No. 08/610,647, filed Mar. 4, 1996, U.S. Pat. No. 5,834,393 corresponding to WO-96/28480, describes supported catalyst components comprising a support material, an organometal compound, an activator compound comprising a cation which is capable of reacting with a transition metal compound to form a catalytically active transition metal complex and a compatible anion having up to 100 nonhydrogen atoms and containing at least one substituent comprising a moiety having an active hydrogen. When combined with a transition metal compound, the resulting supported catalysts are very useful addition polymerization catalysts.
It would be desirable to provide a solid catalyst and solid catalyst dispersions, and components or precursors therefore which do not require an alumoxane component and which can be used in particle formation polymerization processes without requiring a support material.
It would also be desirable to provide a solid catalyst, including precursors therefor, which when used in a polymerization process are capable of producing polymers at good catalyst efficiencies.
It is a further object to provide a solid catalyst, including precursors therefore which when used in a particle forming polymerization process give reduced amounts of particles of undesired size and morphology. It is yet a further object to provide a solid catalyst, including precursors therefore, which when used in a particle forming polymerization process prevents or largely removes the problem of formation of polymer deposits at reactor walls and other moving parts in the reactor.
It is yet a further object to provide a solid catalyst and polymerization process that is capable of forming polymers in the form of free flowing powder or particles.
It is another object to provide a method for making a solid catalyst without requiring recovery or purification steps.
It is a further object to provide a solid catalyst which further comprises a support material.
One or several of these objects are accomplished by the embodiments of the present invention described hereinafter.